Casein interaction with lipid membranes: Are the phase state or charge density of the phospholipids affecting protein adsorption?
Casein micelles are ~200 nm electronegative particles that constitute 80 wt% of the milk proteins. During synthesis in the lactating mammary cells, caseins are thought to interact in the form of ~20 nm assemblies, directly with the biological membranes of the endoplasmic reticulum and/or the Golgi a...
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Published in | Biochimica et biophysica acta. Biomembranes Vol. 1860; no. 12; pp. 2588 - 2598 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
01.12.2018
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Casein micelles are ~200 nm electronegative particles that constitute 80 wt% of the milk proteins. During synthesis in the lactating mammary cells, caseins are thought to interact in the form of ~20 nm assemblies, directly with the biological membranes of the endoplasmic reticulum and/or the Golgi apparatus. However, conditions that drive this interaction are not yet known. Atomic force microscopy imaging and force spectroscopy were used to directly observe the adsorption of casein particles on supported phospholipid bilayers with controlled compositions to vary their phase state and surface charge density, as verified by X-ray diffraction and zetametry. At pH 6.7, the casein particles adsorbed onto bilayer phases with zwitterionic and liquid-disordered phospholipid molecules, but not on phases with anionic or ordered phospholipids. Furthermore, the presence of adsorbed caseins altered the stability of the yet exposed bilayer. Considering their respective compositions and symmetry/asymmetry, these results cast light on the possible interactions of casein assemblies with the organelles' membranes of the lactating mammary cells.
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•Negatively charged 20-nm casein particles interact with membranes on milk synthesis.•Adsorption of individual casein particles onto lipid bilayers is observed using AFM.•Casein particles do not adsorb onto densely packed phospholipids in ordered phase.•Casein particles do not adsorb onto anionic phospholipids, even in disordered phase.•Casein particles adsorb onto zwitterionic and disordered phospholipid phase. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0005-2736 1879-2642 |
DOI: | 10.1016/j.bbamem.2018.09.016 |